import 

java.util.*;

/**

 

* Created by Daxin on 2017/8/19.

 

* <p/>

 

* 奶牛排队饮水问题

 

* 输入：n牛的数目，然后n个整数表示牛的序号

 

* 输出：输出交换最少次数

 

* <p/>

 

* 例如一个测试用例：9<br>

 

* 2,2,1,3,3,3,2,3,1<br>

 

* 输出：4

 

*

 

*在线题目地址：http://www.hustoj.com/oj/problem.php?id=1056

 

*

 

*

 

*/

public 

class 

CattleSortWater {

    

public 

static 

void 

main(String[] args) {

//        int[] nums = {2, 2, 1, 3, 3, 3, 2, 3, 1};

        

Scanner cin = 

new 

Scanner(System.in);

        

int 

n = cin.nextInt();

        

int

[] nums = 

new 

int

[n];

        

for 

(

int 

i = 

0

; i < n; i++) {

            

nums[i] = cin.nextInt();

        

}

        

System.out.println(solve(nums));

//        System.out.println(Arrays.toString(nums));

    

}

    

public 

static 

int 

solve(

int

[] nums) {

        

int 

result = 

0

;

        

Map<Integer, Integer> wcount = 

new 

TreeMap<>();

        

Map<Integer, Integer> range = 

new 

TreeMap<>();

        

for 

(

int 

num : nums) {

            

Integer tmp = wcount.get(num);

            

wcount.put(num, tmp == 

null 

? 

1 

: tmp + 

1

);

        

}

        

Set<Integer> set = wcount.keySet();

        

int 

pre = 

0

;

        

for 

(

int 

i : set) {

            

int 

tmp = wcount.get(i) + pre;

            

range.put(i, tmp);

            

pre = tmp;

        

}

        

for 

(

int 

num : set) {

            

int 

times = wcount.get(num);

            

int 

ran = range.get(num);

            

for 

(

int 

i = ran - 

1

, t = times; t > 

0

; t--, i--) {

                

if 

(nums[i] != num) {

                    

int 

r = get(nums, range.get(nums[i]), wcount.get(nums[i]), num);

                    

if 

(r != -

1

) { 

//在nums[i] 区间中寻找到了num

                        

int 

tmp = nums[r];

                        

nums[r] = nums[i];

                        

nums[i] = tmp;

                        

result++;

                    

} 

else 

{

// 在希望区间没有找到，进行余下遇见全扫描

                        

int 

rr = getRange(nums, ran, num,range.get(nums[i])-wcount.get(nums[i]),range.get(nums[i]));

                        

if 

(rr != -

1

) {

                            

int 

tmp = nums[rr];

                            

nums[rr] = nums[i];

                            

nums[i] = tmp;

                            

result++;

                        

}

                    

}

                

}

            

}

        

}

        

return 

result;

    

}

    

/**

     

*

     

* @param nums 数组

     

* @param range 结束的下标

     

* @param times 出现的次数，range-times就是起始下标

     

* @param expect 希望查找的希望值

     

* @return

     

*/

    

public 

static 

int 

get(

int

[] nums, 

int 

range, 

int 

times, 

int 

expect) {

        

for 

(

int 

i = range - 

1

, t = times; t > 

0

; t--, i--) {

            

if 

(nums[i] == expect) {

                

return 

i;

            

}

        

}

        

return 

-

1

;

    

}

    

/**

     

*

     

* @param nums 数组

     

* @param start 查找的起始位置，结束位置是数组的结束

     

* @param expect 期望寻找到的值

     

* @param exceptStart 排除区域的起始下标

     

* @param exceptEnd 排除区域的结束下标

     

* @return 返回下标

     

*/

    

public 

static 

int 

getRange(

int

[] nums, 

int 

start, 

int 

expect,

int 

exceptStart,

int 

exceptEnd) {

        

for 

(; start < nums.length; start++) {

            

if

(start>=exceptStart&&start<exceptEnd)

                

continue

;

            

if 

(nums[start] == expect) {

                

return 

start;

            

}

        

}

        

return 

-

1

;

    

}

}